The Search for Gravitational Waves

Posted in The Universe and Stuff with tags , , on February 8, 2016 by telescoper

Regardless of what will or will not be announced on Thursday, I thought it would be worth sharing this nice colloquium talk by Dr Alan Weinstein of Caltech about the search for gravitational waves, featuring the Laser Interferometric Gravitational-wave Observatory (LIGO). I’ve picked this not only because it’s a nice and comprehensive overview, but also that Professor Weinstein doesn’t call them gravity waves!



The Owl

Posted in Poetry with tags , , on February 7, 2016 by telescoper

Downhill I came, hungry, and yet not starved,
Cold, yet had heat within me that was proof
Against the north wind; tired, yet so that rest
Had seemed the sweetest thing under a roof. 

Then at the inn I had food, fire, and rest,
Knowing how hungry, cold, and tired was I.
All of the night was quite barred out except
An owl’s cry, a most melancholy cry. 

Shaken out long and clear upon the hill
No merry note, nor cause of merriment,
But one telling me plain what I escaped
And others could not, that night, as in I went. 

And salted was my food, and my repose,
Salted and sobered too, by the bird’s voice
Speaking for all who lay under the stars,
Soldiers and poor, unable to rejoice.

by Edward Thomas (1878-1917)

LIGO Newsflash

Posted in The Universe and Stuff with tags , on February 5, 2016 by telescoper

This morning I heard the same rumour from two distinct (and possibly independent) sources. That’s not enough to prove that the rumour is true, but perhaps enough to make it  repeating here.

The rumour is that, on Thursday 11th February in Washington DC at 10.40am local time (15.40 GMT), the Laser Interferometry Gravitational Wave Observatory (LIGO) will announce the direct experimental detection of gravitational waves.

If true this is immensely exciting, but I reiterate that it is, for the time being at least, only a rumour.

I will add more as soon as I get it. Please feel free to provide updates through the comments. Likewise if you have information to the contrary…


Measuring the lack of impact of journal papers

Posted in Open Access with tags , , , on February 4, 2016 by telescoper

I’ve been involved in a depressing discussion on the Astronomers facebook page, part of which was about the widespread use of Journal Impact factors by appointments panels, grant agencies, promotion committees, and so on. It is argued (by some) that younger researchers should be discouraged from publishing in, e.g., the Open Journal of Astrophysics, because it doesn’t have an impact factor and they would therefore be jeopardising their research career. In fact it takes two years for new journal to acquire an impact factor so if you take this advice seriously nobody should ever publish in any new journal.

For the record, I will state that no promotion committee, grant panel or appointment process I’ve ever been involved in has even mentioned impact factors. However, it appears that some do, despite the fact that they are demonstrably worse than useless at measuring the quality of publications. You can find comprehensive debunking of impact factors and exposure of their flaws all over the internet if you care to look: a good place to start is Stephen Curry’s article here.  I’d make an additional point here, which is that the impact factor uses citation information for the journal as a whole as a sort of proxy measure of the research quality of papers publish in it. But why on Earth should one do this when citation information for each paper is freely available? Why use a proxy when it’s trivial to measure the real thing?

The basic statistical flaw behind impact factors is that they are based on the arithmetic mean number of citations per paper. Since the distribution of citations in all journals is very skewed, this number is dragged upwards by a few papers with extremely large numbers of citations. In fact, most papers published have many few citations than the impact factor of a journal. It’s all very misleading, especially when used as a marketing tool by cynical academic publishers.

Thinking about this on the bus on my way into work this morning I decided to suggest a couple of bibliometric indices that should help put impact factors into context. I urge relevant people to calculate these for their favourite journals:

  • The Dead Paper Fraction (DPF). This is defined to be the fraction of papers published in the journal that receive no citations at all in the census period.  For journals with an impact factor of a few, this is probably a majority of the papers published.
  • The Unreliability of Impact Factor Factor (UIFF). This is defined to be the fraction of papers with fewer citations than the Impact Factor. For many journals this is most of their papers, and the larger this fraction is the more unreliable their Impact Factor is.

Another usefel measure for individual papers is

  • The Corrected Impact Factor. If a paper with a number N of actual citations is published in a journal with impact factor I then the corrected impact factor is C=N-I. For a deeply uninteresting paper published in a flashily hyped journal this will be large and negative, and should be viewed accordingly by relevant panels.

Other suggestions for citation metrics less stupid than the impact factor are welcome through the comments box…


On Religion

Posted in Uncategorized with tags , , on February 3, 2016 by telescoper


Frederick Douglass and the Freedom of Newcastle

Posted in History with tags , , on February 2, 2016 by telescoper

You can learn a lot by looking at Google, even if you don’t use it to search for anything.

I found out – via the Twitter feed of Bonnie Greer – that yesterday’s Google Doodle was this:


The picture is a representation of Frederick Douglass (1818-1895), whose name was quite new to me until yesterday but whose remarkable life story turns out to have a strong connection with my home town of Newcastle upon Tyne.

Douglass was a prominent social reformer and campaigner against slavery, and for other forms of social justice, including equal rights for women. The most famous expression of his political philosophy is the following quote:

I would unite with anybody to do right and with nobody to do wrong.

Once a slave himself, Douglass escaped from bondage in 1838 and, while on the run, wrote his first autobiography Narrative of the Life of Frederick Douglass, an American Slave which quickly became a best seller on both sides of the Atlantic. He eventually made his way to England, where he went on a speaking tour,  impressing audiences around the country with the power of his oratory, his obvious intellect, and the conviction with which he held his political beliefs.

Slavery was unlawful under English common law at that time so technically Douglass was a free man from the moment he set foot in England, but the same would not be true if he returned to America. His English supporters wanted him to remain here, but he had a wife and three children in the United States and wanted to return and continue the campaign against slavery there. But as soon as he set foot back in America he was likely to be seized and returned to his “owner”.

Then, in a remarkably generous gesture, the people of Newcastle upon Tyne solved his problem. They collected enough money to pay his “owner”, Thomas Auld, for his freedom. He returned to America in 1847, a free man, where he remained true to his beliefs and spent the next 48 years continuing his various campaigns. He died of a stroke in 1895, aged 77.

Frederick Douglass was undoubtedly a remarkable man, passionate and courageous with a great gift for public speaking. A Google Doodle is a small honour for such a hero but I’m sure it has at least led to many others besides myself finding out just a little bit more about him.

And if you’ll forgive me for saying so, it also gives me yet another reason to be proud to be a Geordie.  Perhaps it’s true that the people of Newcastle upon Tyne are the most generous in the UK

P.S. Newcastle upon Tyne is not in the Midlands.


Preparing for a PhD Interview in Physics

Posted in Biographical, Education, The Universe and Stuff with tags , , , on February 1, 2016 by telescoper

The other day I was chatting to a group of our 4th-year MPhys students about the process for applying  (and hopefully being interviewed) for a PhD. This is the time when students in the UK have started to apply and are awaiting decisions on whether they have to go for an interview. Final decisions are usually made by the end of March so those with interviews have a busy couple of months coming up.

I actually quite enjoy doing PhD interviews, because that involves giving excellent young scientists their first step on the ladder towards a research career. I’m sure it’s not so pleasant for the candidates though. Nerves sometimes get the better of the students in these interviews, but experienced interviewers can calibrate for that. And if you’re nervous, it means that you care…

Anyone reading this who is nervous about doing a PhD interview (or has experienced nerves in one they’ve already had) might reflect on my experience when I was called to interview for a PhD place in Astronomy at the University of Manchester way back in 1985. I was very nervous before that, and arrived very early for my grilling. I was told to wait in a sort of ante-room as the previous interview had only just started. I started to read a textbook I had brought with me. About five minutes later, the door of the interview room opened and the interviewers, Franz Kahn and John Dyson, both of whom are sadly no longer with us, carried out the unconscious body of the previous candidate. It turned out that, after a couple of friendly preliminary questions, the two Professors had handed the candidate a piece of chalk and told him to go to the blackboard  to work something out, at which point said candidate had fainted. When it was my turn to be handed the chalk I toyed with the idea of staging a mock swoon, but resisted the temptation.

The question, in case you’re interested, was to estimate the angle through which light  is deflected by the Sun’s gravity. I hadn’t done any general relativity in my undergraduate degree, so just did it by dimensional analysis which is easy because an angle is dimensionless. That gets you within a factor of a two of the correct answer which, in those days, was pretty goood going for cosmology. That seemed to go down well and they offered me a place … which I turned down in favour of Sussex.

In those days, before detailed information about research in University departments was available online, the interview generally consisted of a discussion of the various projects available and a few odd questions about Physics (and possible Astronomy) to see if the candidate was able to think on their feet (i.e. without fainting).

Nowadays it’s a bit different. You can still expect a bit of questioning about undergraduate material but that is normally preceded by the chance to talk about your final-year project. One reason for that is that selectors are interested in project work because it can provide evidence of an aptitude for research. The other is simply that it gives the candidate a chance to get over any initial nerves by talking about something that they hopefully know well, as they will have been working on it for some time.

My first piece advice for students who have been offered an interview, therefore, is to prepare a short (~10 minute) verbal summary of your project work so you’re not wrong-footed if asked to talk about it.

Students nowadays are also expected to know a bit more about the thesis topic in advance, so my second tip is to  read up a bit of background so you can talk reasonably intelligently about the proposed research. If, for example, you have decided to work on Dark Energy (as many seem to these days), you won’t come across very well if you don’t know what the main issues are. What’s the observational evidence? What kind of theories are there? What are the open questions? Same goes for other fields. It also will do no harm if you read a couple of recent papers by your prospective supervisor, for reasons of flattery if nothing else.

Anyway, I think those are the two main things. If anyone has other advice to offer prospective PhD students, please feel free to add via the comments box.





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